Storage stability of photoinitiators

1. A compound of formula (I)

R 1 is hydrogen or alkyl;

R 2 is C 1 -C 4 alkoxy or a morpholino radical; and

R 3 is hydrogen or C 1 -C 4 alkoxy.

2. A compound of formula (I) according to claim 1 , wherein

R 1 is hydrogen or C 1 -C 4 alkyl, especially methyl;

R 2 is methoxy or a morpholino radical; and

R 3 is hydrogen or methoxy.

3. A compound of formula (I) according to claim 1

4. A mixture of a compound of formula (I), as defined in claim 1 , with a compound of formula (II)

R 1 , R 2 and R 3 are as defined in claim 1 .

5. A mixture according to claim 4 , containing from 0.1 to 10% of a compound of formula (I)

R 1 is hydrogen or alkyl:

R 2 is C 1 -C 4 alkoxy or a morpholino radical; and

R 3 is hydrogen or C 1 -C 4 alkoxy

and from 90 to 99.9% of a compound of formula (II).

6. A mixture of a compound of formula (I) with a compound of formula (II),

R 1 , R 2 and R 3 are as defined in claim 1

comprising

a compound of formula (I) and a compound of formula (II) wherein in each case R 1 is methyl, R 2 is a morpholino radical and R 3 is hydrogen;

or comprising

a compound of formula (I) and a compound of formula (II) wherein in each case R 1 is hydrogen, R 2 is a morpholino radical and R 3 is hydrogen;

or comprising

a compound of formula (I) and a compound of formula (II) wherein in each case R 1 is hydrogen and R 2 and R 3 are methoxy.

7. A method of improving the storage stability of a formulation comprising a compound of formula (II) as defined in claim 4 , wherein at least one compound of formula (I)

R 1 is hydrogen or alkyl;

R 2 is C 1 -C 4 alkoxy or a morpholino radical; and

R 3 is hydrogen or C 1 -C 4 alkoxy

is added to the formulation.

8. A photopolymerisable composition comprising

(A) at least one ethylenically unsaturated photopolymerisable compound,

(B) at least one photoinitiator compound of formula (II),

R 1 , R 2 and R 3 are as defined in claim 1 ,

and

(C) as storage-stability improver at least one compound of formula (I) as defined in claim 1 .

9. A composition according to claim 8 , comprising, in addition to component (B), further photoinitiator(s) (E) and/or additive(s) (D).

10. A composition according to claim 8 , containing from 0.05 to 20% by weight of photoinitiator component (B), or from 0.05 to 20% by weight of photoinitiator components (B)+(E), based on the composition.

11. A process for the photopolymerisation of non-volatile monomeric, oligomeric or polymeric compounds having at least one ethylenically unsaturated double bond, wherein a composition according to claim 8 is irradiated with light in a range of from 200 to 600 nm.

12. A process according to claim 11 for the production of pigmented and non-pigmented surface coatings, printing inks, screen-printing inks, offset printing inks, flexographic printing inks, UV-curable ink-jet inks, powder coatings, printing plates, adhesives, dental compounds, light waveguides, optical switches, color-testing systems, composite materials, glass fiber cable coatings, screen-printing stencils, resist materials, color filters, gel coats (fine layers), for encapsulating electrical and electronic components, for the production of magnetic recording materials, for the production of three-dimensional articles by means of stereolithography, for the production of photographic reproductions, image-recording material, for holographic recordings, for the production of decolorising materials, for the production of decolorising materials for image-recording materials, for the production of image-recording materials using microcapsules.

13. A coated substrate that has been coated on at least one surface with a composition according to claim 8 .

14. A base-catalysed-curable composition comprising

(F) at least one base-catalysed-polymerisable or polycondensable compound;

(B) at least one photoinitiator compound of formula (II);

R 1 , R 2 and R 3 are as defined in claim 1 ,

and

(C) as storage-stability improver at least one compound of formula (I) as defined in claim 1 , and

(D1) optionally a sensitiser compound.

15. A process for the production of pigmented and non-pigmented surface coatings, protective coatings, basecoats, priming varnishes, primers, topcoats, coating varnishes, automotive repair coatings, decorative coatings, UV-curable powder coatings, UV-curable ink-jet inks, negative resists or printing plates by base-catalysed curing of a compositon according to claim 14 .